Method and apparatus for thermally decomposing refuse

ABSTRACT

A method and apparatus for thermally refuse (pyrolysis is the process of chemically decomposing an organic substance by heating it in an oxygen deficient atmosphere) containing a random mixture of organic and inorganic materials. The apparatus includes an upright cylindrical furnace, a refuse chute having at the uppermost part of the furnace doors which are constructed so as to be always able to shut off the outside atmosphere, combustible gas outlet located in the middle of the furnace, a heat molten material bath located at the lowermost part of the furnace, a means for directly heating the heat molten material in the tank, exhaust openings formed respectively in the middle and lower parts of the tank. Materials chiefly composed of metallic oxides are kept molten in the molten material bath shut off from the outside atmosphere, the combustible gas byproduct of the pyrolyzed organic materials in the refuse dropped into the bath is taken outside the bath and the silicious byproduct and metallic byproduct of the pyrolyzed inorganic materials in the refuse are taken outside the bath respectively from above and below the molten material.

United States Patent 1 Nakamura et al.

14 1 Oct. 15, 1974 METHOD AND APPARATUS FOR THERMALLY DECOMPOSING REFUSE[75] lnventors: Takezo Nakamura, Amagasaki;

-Yuki0 lwasaki, Takarazuka, both of Japan [73] Assignee: Shinmeiwa KogyoKabushiki Kaisha, Toyko, Japan [22] Filed: June 15, 1973 [21'] Appl.No.: 370,467

[30] Foreign Application Priority Data June 17, 1972 Japan 47 60579Sept. 7, 1972 Japan 47-87872 Nov. 15, 1972 Japan 47-114416 Mar. 29, 1973Japan 48-36542 52 I vs. c1, 110/8 c, 110/8E, 110/17 [51] Int. Cl. F23g7/00 [58] Field of Search, 110/8 R, 8 E, 18 R, 18 E, 110/11, 17

[56] References Cited UNITED STATES PATENTS 1,184,351 5/1916 Kidwell 11017 3,592,151 711971 Webber 3,744,438 7/1973 Southwick 110/18 PrimaryExaminer-Kenneth W. Sprague Attorney, Agent, or Firm-Holman & Stern 5 77 ABSTRACT A method and apparatus for thermally refuse (pyrolysis is theprocess of chemically decomposing an organic substance by heating it inan oxygen deficient atmosphere) containing a random mixture of organicand inorganic materials. The apparatus includes an upright cylindricalfurnace, a refuse chute having at the uppermost part of the furnacedoors which are constructed so as to be always able to shut off theoutside atmosphere, combustible gas outlet located in the middle of thefurnace, a heat molten material bath located at the lowermost part ofthe furnace, a means for directly heating the heat molten material inthe.

tank, exhaust openings formed respectively in the middle and lower partsof the tank. Materials chiefly composed of metallic oxides are keptmolten in the molten material bath shut off from the outside atmosphere,the combustible gas byproduct of the pyrolyzed organic materials in therefuse dropped into the bath is taken outside the bath and the siliciousbyproduct and metallic byproduct of the pyrolyzed inorganic materials inthe refuse are taken outside the bath respectively from above and belowthe molten material.

' 9 Claims, 5 Drawing Figures PAIENTED w 1 974 sum ear 3 Fig.4

PATENTEDBET 1 5:974

saw an; 3

METHOD AND APPARATUS FOR THERMALLY DECOMPOSING REFUSE BACKGROUND OF THEINVENTION-DESCRIPTION OF THE PRIOR ART Various proposals have heretoforebeen made and carried out as to a method and apparatus for disposing ofrefuse. Among such proposals are a method and apparatus for incineratingthe refuse that have long been practised. According to such method andapparatus, for example, the refuse is merely burnt by hot blast or oilburner. But in resorting to a means of burning little use is made of thegas generated during burning, and the only thing that can be turned intoaccount is noncombustibles and heat, and moreover a means for preventingenvironmental disruption such as a means for disposing of exhaust gas, ameans for collecting duct, etc. is required.

When grates are used in the incinerating means, the grates show atendency to be plugged and distorted or disintegrated, with thedisadvantageous result that immense labor in maintenance and repair ofthe grates as well as extended periods of dowmtime during the repair andmaintenance is required. The prior art that has obviated the drawkbacksof the kind described is US. Pat.

From the viewpoint of effective use of resources on earth, active andintense studies have recently been continued as to the development ofthe technique of recycling and reusing the components of refuse ofvarious kinds. One of the methods in response thereto of recycling ofrefuse by pyrolysis is to shut off the refuse from the outsideatmosphere and heat the same from outside, but for reasons of art it istechnically difficultto provide a pyrolysis temperature of higher thanabout 900C, with the result that an organic material is pyro- 7lyzedbutan inorganic materi al i pot decomposed.

SUMMARY OF THE INVENTION This invention relates to a method andapparatus for pyrolysis of refuse, and more particularly to a method andapparatus for charging refuse into a specified mol-' ten slag tank inthe state of the outside atmosphere being shut off and for pyrolysis ofthe refuse without causing a combustion stage.

A primary object of this invention is to make effective use of refuse bydroping the refuse into a hightemperature molten slag bath regardless ofthe kind of refuse and pyrolyzing the refuse at high temperatures insuch a manner that the organic matter in the refuse is effectively usedin the form of gasified byproduct and the inorganic matter is melted andtapped off singly or together with the molten slag and used repeatedly.

Another object of this invention is to pyrolyze refuse 65 withoutsorting or crushing the refuse.

Still another object of the invention is to pyrolyze refuse within ashorter period of time than was conventionally needed by a markedimprovement in heat efficiency.

A further object of the invention is to increase the calorific value ofgas generated in conjunction with the pyrolysis of the refuse and tomake effective use of the calorific value.

Still further object of the invention is to prevent the formation ofclinkers by high temperatures produced in the bath.

Yet further object of the invention is to cover the energy necessary forthe operation of the furnace by the heat quantity of the gas generated.

Yet another object of the invention is to continuously pyrolyze refuseby producing superhigh temperature nonoxygen atmosphere of the order of1,600C by a direct charge slag bath type pyrolysis apparatus.

According to the invention, a magmalike material (which is a metallicoxide and under which are ineluded SiO A1 0 CaO, MgO, FeO, Fe O TiO etc.etc., and slag, wasteglass and the like belong also in this category) isinitially dropped into the bottom of a closed bath and is melted andsoftened by an electrical or chemical means.

Melting and decomposition temperature of the magma-like material isconsiderably high, but when the temperature is raised above 1,000C, thematerial becomes softened. And at normal temperature the mate-' rial isa nonconductor, but when it is in a molten state, the material becomes aconductor of electricity as is seen in electro-slag welding and directcharge melting of glass. Accordingly, when the magmalike material wassoftened tosuch a degree as to permit the same to be energized with acurrent, the material is energized by direct contact of electrodestherewith, to thereby expedite melting and use the molten material as asource of heat generation.

According to the invention, preliminaries such as sorting, crushing,etc., of refuse are not at all necessary, and not only solid refuse butalso liquid refuse and refuse to be liquefied by heating, such as forexample waste oil, waste plastics, can be disposed of.

According to the invention, as soon as municipal refuse is collected andtransported, it can immediately by charged into a closed decompositionbath and disposed of at high temperatures, and hence an offensive odoris completely decomposed. Accordingly, the apparatus of the inventionhas little or no need of equipment for the prevention of environmentaldisruption caused by air, waste water and soil pollution that have beenproblems to the conventional refuse furnaces. Chloric acid originatingfrom polyvinyl chloride, sulphurous acid gas from a rubber vulcaninzingagent, hydrogen sulfide, etc. are neutralized with a large amount ofammonium produced from protein of scraps of food and melamine resinsinto nonpoisonous salts such as NH Cl, (NH SO (NH S, etc., and hencethere is no fear of environmental pollution by waste water either.

Since the bath is operated at superhigh temperatures, there is nopossibility of clinkers being produced, and deterious material, such aspolychlorinated biphenyl, which is considered difficult to decompose, iscompletely decomposed into a harmless material, and a nitrogen oxideattendant upon high-temperature incineration is not produced because ofpyrolysis in a nonoxygen atmosphere. A greater part of nitrogen oxide isnitrogen monoxide, and temperature and concentration of oxygen have muchto do with the production of nitrogen monoxide, but even at hightemperatures the amount of nitrogen monoxide produced is small whencombustion is effected at an air ratio of less than one. According tothe system of the invention, there IS no oxygen existing in the bathexcept that brought in to- 4 In this manner the raw material componentsof the meltable material 6 are all metallic oxides, which are insulatorsat normal temperature but which become conductors of electricitybecause, as well known, the oscillation of molecules and ions given bythe high temgether with the refuse charged into the furnace, andperature of the plasma are 5 disperses electron waves hence what littleoxygen exists in the bath is low in cont thereby reduce resistance.Accordingly, after the centration, and because oxygen reacts withhydrocarmeltable material 6 has been melted, are 5 is produced bon andhydrogen sooner than with nitrogen, no n obetween the track 2 and themolten material 6 in the gen monoxide is allowed to be produced. Inaddition, same manner as it wa in FIG 1, Thus, the molten masince theeffects of nitrogen in the molecule of refuse terial 6 is increased intemperature, but about 2,000C become smaller in proportion to anincrease in temperis the maximum temperature the material 6 will attainature, n0 nitrogen oxide is p o u ed o, because, in the light of thefire resistance of the walls of the furuhllke the System in whlchheallhg lakes Place Outside nace tank 1 and of the melting temperatureof the rethe bath, a heat Source iS provide inside the furnace i5 fuse.After the furnace has been brought into this state, of the invention,there is little or no difficulty in point fuse is dro ped downwardlythrough the chute 7. The of technical engineering when a furnace isincreased in refuse dr pp d i inst ntly melted, General town refusesize. is made up of some percentage of inorganic matters These and otherobjects, advantages and features of and a greater percentage of organicmatters, the inorlhe lhvehlloh Wlll become more PP from a COII- 2 ganicmatters being iron and aluminum in large quantisideration of thefollowing description taken in coni d b i f n l d at h hi h temperatured junction with the accompanying dra g wherein pr scribed above andmixed into the molten material 6. On ferl'ed embodiments arelllusll'aled y y of p the other hand, the organic matters are varied inkind D l m but small in the number of components and they are BRlEFDESCRlPTlON OF THE DRAWlNG carbon, hydrogen, oxygen, nitrogen, sulfur,phospho- Ih thedrawings; rus, halogens and a small amount of metallicelements FIG. I is a diagrammatic sectional view showing the aslmpul'ltles- Accordlhglyv also h the P 'g principle of this invention;matters, metals are melted and mixed likewise into the FIG. 2 is a blockdiagram of a reclaiming system assomalel'lal Olher Components are mostlyg ciated with a bath of this invention; ifledand tapped off through anoutlet 8 to a known pro- FIG. 3 is another diagrammatic sectional viewshowducllon (El/lee as shown m ing the principle of the invention; Thedevice 10 is adapted to separate the gas thus col- FIG. 4 is a frontelevation, partly in section, of an emleqed and Produce the a capable 9bemg bodiment of the invention; and utilized, and a gas normallyimpossible of practical use FIG, 5 is a front elevation, partly insection, of a mods collected as by dust collector l1 and exhaustedoutified embodiment of the invention 6 side in such a manner as toprevent environmental polr t "mlution. Also, since the molten material 618 increased In DESCRIPTION OF THE PREFERRED volume, it is flowed outthrough an outlet 9, colled by EMBODIMENTS a solid producing device 12and collected as a solid consisting chiefly of a magma-like material.The solid Referrlhg how to the drawlhgs and Particularly to matter thusobtained may be used for reclamation, enthere is Show" a furnace lahk 1Constructed of gineering and building works. The heat resulting fromrefractory material in which is beforehand received a h production f theSolid matter i last i part, but can meltable material 6 havinginexpensive metals such as be utilized f the most pal-L For example, thepower iron mixed thereinto and consisting of rock and slag as generatedby driving a generator 13 can be utilized f lls Chlef compohehl- APlasma are torch Plasma arc the aforestated heat source for heating. Themolten electrode 3 and POWer Source 4 Plasma arc, as material 6naturally sets up a convection current but shown, are located as a heatsource for heating. At the may electromagneticany be brought i f ed itop of the furnace tank 1 are formed a refuse chute 7 lation as b hi hfrequency heating. and a gas Ohllel 8 and Oh the Slde of the tank 1 isIn the embodiment described above, for example the formed a moltenmalel'lal Outlet vollage l5 lmpl'essed heat source for heating need notbe limited to a plasma y Power Source 4 between the torch 2 and the elecare along but may be replaced by various known heat tl'Ode 3 to start aplasma are 5 a known method. The ources uch as for example an ordinaryare Joule are 5 is generated between the t0rC 2 and electrode 3 heatresulting from an electric current directly through before the meltablematerial6is molten. The following the material 6, high frequency heatingand the like, examples may be applied as the raw material composiwhichcan heat the material 6 to high temperatures. tion of the meltablematerial 6. Shown in FIG. 3is an embodiment in which a vitre- COmPOShiOH(P by g ous meltable material is chiefly used and in which the Example:sio, MnO CaO MgO Ai,o car, FeO s i TIC), (A) 35% 24 5 6 l3 16 1.5 0.15015 a 41% i2 20 5 4 l8 ExzimifiQ no, N3 0 ll x 0 CaO 'ngo xijo',"6361""216" F6 0,; (C) 71.6% 15 10.7 2.02 0.48 0.14 (D) 67.5% 6.77 3.646.82 0.1 6.53 7.93 0.7 0.08

Example: sio, Ano F56. FeO M o E56 Nine Tio v.6 A i m (E) 73% I5 5 6 I(F) 60% i5 3 3.5 4 5 l embodiment is illustrated in greater detail thanthe one in FIG. 1. The furnace tank used is the same in structure asthat in FIG. 1. The furnace tank 1 is provided with a chute 7 and anexhaust outlet 8 each having a cover. The numerals 2 and 3 designateelectrodes inserted into a meltable material 6; a power source 4 givinga potential difference to the electrodes 2 and 3; and 5 designates aninitial heating element made up of a plasma jet torch. The raw materialof the meltable material consists chiefly of a vitreous substance.Scraps of ordinary glass are used for reasons of economy. In addition, asubstance such as soda water glass, potash water glass, which havefluidity at normal temperature; and a vitreous substances such assoda-lime silica glass, neutral glass, boric silica glass, Pyrex glassand so on may all be used.

The raw material of the meltable material 6 is heated by a plasma jettorch 5 in the furnace 'tank 1 and is given fluidity. As well known,vitreous substance, when it is non-fluid, is a nonconductor ofelectricity but becomes a good conductor, when it is molten into a fluidmatter. Accordingly, when a potential difference is given by a powersource 4 to the electrodes 2 and 3, the molten material 6 is energizedwith a current and heated by Joule heat to high temperatures. Then, whenthe refuse to be pyrolyzed is dropped through a chute 7, the refuse ispyrolyzed by the high-temperature molten material 6. In this case, thecovers of chute 7 and exhaust outlet 8 are closed so as to pyrolyze andpyrolyze the refuse in the state of the inside of the bath being shutoff from the air.

An experiment effected by the inventor showed that 500 kg of scraps ofordinary glass was used as the meltable material 6, was melted attemperatures in the range of about 500 to 700C to cover a surface areaof l m and a depth of cm in the bath, and electrodes 2 and 3 wereinserted into the molten material so as to make a flow of electricity asuniform as possible, and

' a potential difference of 200v was given and a current hightemperature is not always necessary for the pyrolysis of the refuse, andthe highest temperature needed is about l,800C, and hence it isadvisable to control power source 4 by use of a thermostat and tothereby maintain the temperature of the material 6 at a high temperatureof a substantially constant degree. However, the refuse dropped sinksdeeper into the molten material 6 and becomes better in conductionefficiency of heat in proportion as the material 6 is increased influidity.

Pyrolysis of refuse by use of the molten material described above showedthat about 250 kg of refuse could be pyrolyzed per hour. The pyrolyzedorganic matters are chiefly hydrogen, carbon monoxide, methane,ethylene, etc., and are exhausted in gas from the furnace, while theinorganic matters are mostly iron, aluminum and are mixed together withthe residues of the organic matters into the molten material 6. Nitrogenoxide was scarcely produced, which showed that prevention ofenvironmental disruption is possible.

FIG. 4 shows an embodiment of an apparatus provided by this invention. Afurnace body generally indicated at 21 is made of refractory materialand is of an 6 upright cylindrical construction. At the topof thefurnace body 21 is mounted a refuse hopper 21a and below the hopper isprovided an air shielding type revolving door 21b adapted to prevent theair from entering the inside of the furnace body 21. Below the revolvingdoor 21b of the furnace body 21 is disposed another revolving door 21fof the same air shielding type. A space in the form of a preheatingchamber 21c between the revolving doors 21b and 21f is naturallysubjected to heat of to 200C. The numeral 21d designates a jacketportion of the outer periphery of the preheating chamber 21c; 21e anoutlet communicating with the preheating chamber 210; 21g anintermediate portion of the furnace body 21, the temperature inside ofwhich furnace body reaches about 500C; 21h an outlet communicating withthe intermediate portion 21 g; and 2li designates a molten material bothin the lowermost part of the furnace body and a discharge outlet 21 jhaving a door is provided at the same height as the tank and anotherdischarge outlet 21k, having a door, is formed at the bottom of the tank2li. The numeral 22 desigriates a cooler, which is adapted to cool thegas from the aforestated outlet 21e with water or the like and tocollect the cooled gas from the outlet 22a. The numeral 23 indicates aheat exchanger, and the air heated by the exchanger 23 is fed by acontrolling blower 24, for example, to the molten material tank 2li orused for other purposes; 25 a control valve interposed in theintermediate portion of the piping between the outlet 21h communicatingwith the intermediate portion 21g of the furnace and the heat exchanger23, said valve 25 being controlled by a sensor 26 that measures a flowrate in the intermediate portion of the aforestated piping; 27 a knownscrubber; 27a an outlet of the scrubber, and a control valve 28 isinterposed in the intermediate portion of the piping between theaforestated outlet 21h and the inlet of the scrubber 27; 29 a sensorthat is designed to detect a pressure difference between the inside ofthe intermediate portion 213 of the furnace body and the atmosphericpressure and is adapted to control the valve 28 to maintain the pressuredifference constant; 30 a hot air blowing-in pipe which is constructedso as to blow hot air from the heat exchanger 23 into the furnace tank2li and which is adapted to measure the temperature inside the furnacetank 211 by a sensor 32 when necessary and to maintain such temperaturesubstantially constant in the range of about l,600 to 1,800C by means ofa control valve 31 interposed in the piping between the heat exchanger23 and the pipe 30. General reference character 33 designates a meansfor directly heating the material inside the bath 33a a plasma torch;and 33b designates two electrodes in said means 33. The material of theelectrodes is a high-temperature resisting material such as graphite andis designed to be automatically extended forwardly in succession inproportion to the wear of the material.

The numeral 34 designates a gas bleeding pipe extending from above theopening of the blowing-in pipe 30 inside the tank 2li to the inlet ofthe scrubber 27; 35 a valve for the bleeding pipe 34; and 36 designatesa molten material.

Now, a description will be made of operation of the invention.Substances, as a raw material for a meltable material consisting chieflyof the aforestated metallic oxides are dropped through the chute 21awhile the revolving doors 21b and 21f are turned. The substancescollected in the tank 211' are melted by starting a torch 3311. Theycome to acquire electric conductivity by resistance being reduced intheir molten state, and accordingly, if continuity is established acrosstwo electrodes 33b while the substances being melted, electric potentialis impressed across the electrodes from a power source (not shown) tothereby melt the substances completely into a molten bath of material36.

Next, the refuse to be pyrolyzed is dropped from the chute 2111 throughthe revolving doors 21b and 2lfinto the furnace body. While the refusedropped is being downwardly moved through the inside of the furnacebody, it is preheated in the preheating chamber 21c heated by the heatof said bath of material 36 and is thus deprived of its moisture. Themoisture thus separated from the refuse passes through the outlet 2le tothe cooler 22, where the moisture is tapped off in the form of waterthrough the outlet 22a. The time during which the refuse is subjected tosaid preheating continues for approximately 10 odd minutes. When therefuse is dropped into the intermediate portion 21g of the furnace bodyand onto the tank 211', it is pyrolyzed without being burnt because ofthe high temperature ranging from l,600 to I,800C of the molten material36 and because of the inside of the furnace body 21 being shut off fromthe air. The time necessary for pyrolysis is about 45 to 90 minutes perton of refuse. Particularly, organic matters are pyrolyzed into a gas,which consists generally of 50 percent hydrogen, 20 percent carbonmonoxide, percent methane, 5 percent ethylene and the like. Thiscombustible gas passes for the most part through the outlet 21h andvalve 28 to the scrubber 27 where it is freed of unnecessary materialand tapped off through the outlet 27a and used for other purposes.Another part of the gas is led to the heat exchanger 23 through theoutlet 21h and valve 25 and, after it has heated the air forcedlysupplied by blower 24, the gas is transferred to a jacket portion 21dand preheats the preheating chamber 210 and is then processed in thescrubber 27. In the meantime, a valve 28 is controlled by a sensor 29 tokeep the inner pressure of the furnace body 21 constant, and a valve 25is controlled by a sensor 26 to control a flow rate of gas in order tocontrol the temperatures of the preheating chamber 21 c and heatexhanger 23.

The inorganic substances in the refuse are pyrolyzed by the hightemperature inside the tank 2li and separated roughly into a siliciousmatter and a metallic matter and are reduced in bulk, and because thesilicious matter becomes less in specific gravity than the moltenmaterial 36, it floats, and because the metallic matter is higher inspecific gravity, it sinks, the silicious matter is removed through theoutlet 2lj at suitable time and the metallic matter is removed throughthe outlet 21k, and both are used for their respective purposes.

Also, in the meantime, hot air from the blower 24 and heat exchanger 23is blown into the tank 2li by the the blowing-in pipe 30 and mixed andburnt together with the combustible gas in this part to thereby maintainthe temperature of the molten heat source 36 economically constant.Also, in this case, a valve 31 may be controlled by a sensor 32 tomaintain said constant temperature, but when there is a possibility ofmaking it impossible to maintain the constant temperature by control ofthe valve 31 alone because the refuse is not uniform in quality, allthat is necessary is to establish continuity across the electrodes 3312by operation of the sensor 32. The gas resulting from the combustiblegas having been burnt by blowing in hot air through the blowing-in pipe30 is exhausted out of the furnace body 21 through a pipe 34 by openingthe valve 35 at suitable time. As described above, one embodiment of theinvention has been described and illustrated, and it should beunderstood that the meltable material may be melted as by using a plasmatorch alone as a heating means 33 or by burning powdered aluminum oriron inside the tank 2li.

FIG. 5 shows an embodiment of the invention in which the heat quantityof the gas obtained by pyrolysis is used as a heat source for themeltable material in the bath. The furnace body in this embodiment is ofthe same structure as that in the embodiment in FIG. 4, and like partsof the furnace body are designated by like reference characters andexplanation of such parts is omitted. In FIG. 5, the numeral designatesa combustion tower connected by piping 40a to an outlet 21h formed inthe intermediate portion 21g corresponding to the upper part of the tank2li of the furnace body. In the intermediate part of the piping 40a isprovided a control valve 28a, which is controlled by a sensor 290adapted to detect a difference between the inner pressure of theintermediate portion 21g of the furnace body and atmospheric pressure inthe manner that the pressure difference therebetween can be keptdefinite. To the combustion tower 40 is also connected an outlet pipe23:: of the heat exchanger 23, and a control valve 41 is providedbetween the outlet pipe 23a and the combustion tower 40.

The control valve 41 includes a sensor 42 adapted to detect the velocityof flow inside the piping 40a between the outlet 21h and the combustiontower 40 and to operate the valve 41 to thereby provide the velocity offlow of a specified ratio to said velocity of flow. A control valve 25interposed in the intermediate portion between the outlet 21h and theheat exchanger 23 is equipped with a sensor adapted to detect thetemperature inside the preheating chamber 21c and to thereby operate thevalve 25 for making the temperature constant (about 100 to 200C in theembodiment illustrated).,The numeral 43 designates a boiler, into thelower part of which hot air by flames ignited in the combustion tower 40is introduced through a pipe 40b. The steam generated is tapped offthrough a steam outlet 43a. The numeral 44 designates a steam generator,for example, a turbine, which is driven by steam fed through the outlet43a and exhaust steam is condensed by a steam condenser 45; 46 a feedwater preheater which preheates the water supplied to the boiler 43 byhot air from the outlet 2le in the upper part of the furnace body; and47 designates a known scrubber designed to dispose of the exhaust fromthe boiler 43, and the exhaust disposed of by the scrubber 47 is let outby exhaust blower 48 through a chimney 49. The power of generator 50driven by the aforestated steam prime mover 44 is supplied to a powersource controlling device 51, the output of which is controlled by asignal from a temperature sensor 52 in the molten slag tank 2li, and theoutput is impressed upon a pair of electrodes 33b disposed on the outerperiphery of the tank 2li.

In the same manner as in the embodiment in H6. 4, the heat source 36 ismelted by flames of a plasma arc torch 33a. After it has been melted,voltage from the generator 50 is impressed between the electrodes 33band 33b to thereby energize the power generation source 36 directly withan electric current and to maintain the source 36 above 1,600C by Jouleheat and keep the same molten. However, in this starting time ofoperation, the prime mover 44 for the generator 50 is not operated, andhence the generator 50 is turned either by another generator (not shown)or by use of other starting power source. When the refuse to bepyrolyzed is transported by a dump turck 38, placed on a conveyor 39 anddropped therefrom into the furnace, it passes through revolving doors21b and 21f in the same manner as in the embodiment in FIG. 4 andreaches the tank 211', where the refuse is pyrolyzed when contacting themolten slag 36 and most of the refuse is changed into a gas. The chiefcomponents of the gas are hydrogen, ethylene, methane, ethane, carbonmonoxide and the like. On the other hand, inorganic matters are alsoultimately pyrolyzed but for the most part become slag and metallicsubstances, which, like the molten slag 36, are conductors ofelectricity at high temperatures and mixed into the molten slag 36 andperform the same function therewith.

The gaseous substance described above goes upward to the intermediateportion 21g and is removed outside through the outlet 21h and a part ofthe substance becomes a heat source for preheating the air forcedlysupplied by blower 24, and on the other hand it preheats the preheatingchamber 21c in the jacket portion 21d and passes through the pipe 40c tothe combustion tower 40. The other part of the gas passes directly tothe combustion tower. While the gas is thus passing through the piping,a valve 25 is controlled by sensor 26 to thereby control the flow rateof the gas in the jacket portion 21d, whereby the temperatures in thepreheating chamber 21c is controlled to about 100 to 200C. Also, a valve28a is controlled by a sensor 29a so as to maintain the pressure insidethe intermediate portion 21g below a specified pressure.

The refuse preheated to temperatures of 100 to 200C within thepreheating chamber 210 is not pyrolyzed but has its moisture removed inthe form of vapor which becomes a heat source of feed water preheater46. Also, the gas produced by decomposition due to heating of the refusein the intermediate portion 21g and tank 21i is fed to the combustiontower 40 as described previously. Since the gas that reaches the tower40 has a high temperature and is combustible, it catches fire throughmixture with a suitable amount of air heated in the heat exchanger 23and attains complete combustion. The flames at this time generates steamin the boiler 43 to thereby drive the prime mover 44, which in turnmoves the generator 50. Combustion exhaust from the boiler 43 isprocessed in the scrubber 47 to prevent secondary pollution, andexhausted by blower 48 from a chimney 49.

Experiments show that the heat quantity required for thermally pyrolysisof municipal refuse at temperatures in the range of 1,600 to 1,800C ison the order of 25 percent of the heat quantity held by the pyrolyzedgas produced by disposal of the municipal refuse. On the other hand, thepower generation equipment at present gives an efficiency of 90 percentin boilers, 45 percent in turbines (including condensers), 98 percent ingenerators. Also, in this invention, the Joule heat provided by directenergization of the molten slag in the furnace bath is a heat sourceused in the thermal pyrolysis described, and the refuse is ultimatelycombined directly in the molten slag, and accordingly the furnace of theinvention is excellent in efficiency of heating. If the furnace body andpiping are sufficiently provided with sufficient heat insulating means,radiation of heat from the walls of furnace and piping is small inamount and the efficiency of heating including the radiation is about 91percent. Accordingly, the efficiency of available thermal energyobtained from the refuse is as represented by 0.9 X 0.45 X 0.98 X 0.910.36 36 percent, and still leaves more than the aforestated 25 percentof heat quantity held by the pyrolyzed gas. Accordingly, the heatquantity required for the pyrolysis of refuse can be compensated morethan enough by the heat quantity of gas produced by pyrolysis of therefuse, with the result that the furnace can thermally be operated inperfectly closed cycles.

In the embodiments described and illustrated above, combustion tower 40,boiler 43, turbine 44 and generator 50 have been used as a powergenerating means, but alternatively a gas turbine may be directly turnedby use of the pyrolysis gas to thereby operate a generator, and itshould be understood that, if MHD (magnetohydrodynamics) generation isput to industrial application, recourse may be had to such type of powergeneration by which the aforestated surplus in heat balance will furtherbe increased. It should be noted that the embodiments described andillustrated are included merely to aid in the understanding of theinvention and that various modifications and replacements withequivalents of the invention may be made without departing from thescope and spirit of the inventionas defined by the appended claims.

What is claimed is:

1. A method of pyrolizing and disposing of refuse comprising the stepsof (A) melting a solid material into a molten bath by heating means inthe lower part of a furnace closed from the outside atmosphere in whichsaid solid material comprises vitreous matter as a component; (B)providing electrodes in said molten bath and energizing the same with anelectrical current to maintain the molten state of the molten material;(C) bringing mixed refuse into contact with said molten bath andpyrolyzing the same; (D) removing a gas produced by pyrolysis of refusefrom said furnace; (E) and extracting components of the refuse that havebeen reduced to a molten material; (F) initially providing a plasmaflame to keep said molten material molten; and, next subjecting saidmolten material to high frequency heating to maintain the moltenmaterial molten.

2. A method according to claim 1, including burning part of the gasproduced from said refuse inside the furnace to retain the heat of themolten material.

3. A method according to claim 1, including generating an electricalcurrent by the heat quantity of gas produced from said refuse, andimpressing current thus generated on the molten material.

4. A method according to claim 1 which includes preheating of all therefuse in closed manner in a preheating chamber shut off from theoutside atmosphere in the upper part of the furnace tank. i

5. An apparatus for use in a method of pyrolyzing and disposing ofrefuse comprising melting a solid material into a molten material byheating means in the lower part of a furnace shut off from the outsideatmosphere, said solid material consisting of vitreous matter as itscomponent, providing electrodes in said molten material and energizingthe same with an electrical current to maintain the molten state of themolten material; bringing all refuse into contact with said moltenmaterialand pyrolyzing the same; removing a gas produced by pyrolysis ofrefuse from said furnace; and extracting components of the refuse thathave been reduced to a molten material; comprising a tank of refractorywalls, a molten material bath of pyrolyzing material in said tank ofrefractory walls; refuse passage means of refractory material openinginto said tank from above the tank; plural door means for shielding thebath from the outside atmosphere disposed in said refuse passage means;a preheating stage between said door means; preheating means for saidpreheating stage; initial heating means provided above the level of thebath of meltable material in the molten material tank; electric heatingmeans for the meltable material disposed in the lower portion of saidbath of molten material in the molten material tank; means forcollecting thermally pyrolyzed gas of refuse connected to the refusepassage means above the molten material tank; and means for collectingmolten refuse disposed in the molten material bath.

6. An apparatus for pyrolyzing refuse according to claim 5 including aheat exchanger, said preheating means includes a means for supplying apreheating gas. said means extending from the means for collectingpyrolyzed gas of refuse and being connected to said preheating means forthe preheating stage through said heat exchanger.

7. An apparatus for pyrolyzing refuse according to claim 6 whichincludes a combustion tower, means conducting the pyrolized gas fromsaid preheating means to said combustion tower, means for supplyingheated air through said heat exchanger to said combustion tower.

8. An apparatus for pyrolyzing refuse according to claim 7 whichincludes a steam generating means connected to receive the combustiongas of said combustion tower and a generator connected to said steamgenerating means.

9. An apparatus for pyrolyzing refuse according to claim 8 whichincludes a power source control means connected to said generator, saidcontrol means being electrically connected to the previously mentionedelectric heating means for the meltable molten bath of

1. A method of pyrolizing and disposing of refuse comprising the stepsof (A) melting a solid material into a molten bath by heating means inthe lower part of a furnace closed from the outside atmosphere in whichsaid solid material comprises vitreous matter as a component; (B)providing electrodes in said molten bath and energizing the same with anelectrical current to maintain the molten state of the molten material;(C) bringing mixed refuse into contact with said molten bath andpyrolyzing the same; (D) removing a gas produced by pyrolysis of refusefrom said furnace; (E) and extracting components of the refuse that havebeen redUced to a molten material; (F) initially providing a plasmaflame to keep said molten material molten; and, next subjecting saidmolten material to high frequency heating to maintain the moltenmaterial molten.
 2. A method according to claim 1, including burningpart of the gas produced from said refuse inside the furnace to retainthe heat of the molten material.
 3. A method according to claim 1,including generating an electrical current by the heat quantity of gasproduced from said refuse, and impressing current thus generated on themolten material.
 4. A method according to claim 1 which includespreheating of all the refuse in closed manner in a preheating chambershut off from the outside atmosphere in the upper part of the furnacetank.
 5. An apparatus for use in a method of pyrolyzing and disposing ofrefuse comprising melting a solid material into a molten material byheating means in the lower part of a furnace shut off from the outsideatmosphere, said solid material consisting of vitreous matter as itscomponent, providing electrodes in said molten material and energizingthe same with an electrical current to maintain the molten state of themolten material; bringing all refuse into contact with said moltenmaterial and pyrolyzing the same; removing a gas produced by pyrolysisof refuse from said furnace; and extracting components of the refusethat have been reduced to a molten material; comprising a tank ofrefractory walls, a molten material bath of pyrolyzing material in saidtank of refractory walls; refuse passage means of refractory materialopening into said tank from above the tank; plural door means forshielding the bath from the outside atmosphere disposed in said refusepassage means; a preheating stage between said door means; preheatingmeans for said preheating stage; initial heating means provided abovethe level of the bath of meltable material in the molten material tank;electric heating means for the meltable material disposed in the lowerportion of said bath of molten material in the molten material tank;means for collecting thermally pyrolyzed gas of refuse connected to therefuse passage means above the molten material tank; and means forcollecting molten refuse disposed in the molten material bath.
 6. Anapparatus for pyrolyzing refuse according to claim 5 including a heatexchanger, said preheating means includes a means for supplying apreheating gas, said means extending from the means for collectingpyrolyzed gas of refuse and being connected to said preheating means forthe preheating stage through said heat exchanger.
 7. An apparatus forpyrolyzing refuse according to claim 6 which includes a combustiontower, means conducting the pyrolized gas from said preheating means tosaid combustion tower, means for supplying heated air through said heatexchanger to said combustion tower.
 8. An apparatus for pyrolyzingrefuse according to claim 7 which includes a steam generating meansconnected to receive the combustion gas of said combustion tower and agenerator connected to said steam generating means.
 9. An apparatus forpyrolyzing refuse according to claim 8 which includes a power sourcecontrol means connected to said generator, and control means beingelectrically connected to the previously mentioned electric heatingmeans for the meltable molten bath of material.